JPH1038902A - Detector for rotational speed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotational speed detector capable of detecting a rotational speed without taking time for adjustment, even if a rotary scale has an eccentricity or strain. SOLUTION: A pulse signal generating means (photosensor) 3 for detecting a plurality of light reflecting elements on a rotary scale 101, and a pulse interval detector 4 generating a rotational pulse signal from this sensor signal are provided. Besides, a phase pulse outputting means 5 which output information on one rotation of a rotor is provided. A coefficient of eccentricity calculating circuit 7 which specifies the regular position of each pulse shifted by the eccentricity of the rotary scale 101 from the output signals of this phase pulse outputting means 5 and the pulse signal generating means 3, and takes a coefficient of eccentricity correction corresponding to each pulse out of a memory is provided. A rotational pulse correcting circuit (multiplier) 8 which corrects the output of the pulse interval detector on the basis of this coefficient of eccentricity correction is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotational speed detecting device, and more particularly to a rotational speed detecting device for detecting a rotational speed of a motor or the like with high accuracy.

[0002]

2. Description of the Related Art Conventionally, many types of rotational speed detecting devices use a photoelectric rotary encoder to detect the period of a detected electric pulse output from an optical sensor as rotational speed information.

FIG. 9 shows an example of a conventional rotation speed detecting device. In FIG. 9, a rotary scale 101
As shown in FIG. 10, the reflection part / non-reflection part (or the transmission part
Non-transmissive portions) are radially arranged at equal intervals, and are fitted and fixed to the rotating shaft 102 via through holes provided at the center thereof. Reflective (or transmissive) optical sensor 1
Reference numeral 03 denotes a light reflecting portion 101a which is placed close to the rotary scale 101 and is of a reflection type (or a transmission type in a transmission state) of the rotary scale 101, and converts the light reflection portion 101a into an electric pulse signal.

The electric pulse output from the optical sensor 103 indicates the time when each light reflecting portion 101a has passed through the sensor, and the interval between pulses is necessary for the adjacent light reflecting portions to pass through the optical sensor 103. Shows the time when it was done. Then, the pulse interval detector 104 detects the pulse interval of the electric pulse signal output from the optical sensor 103.

Here, assuming that the pulse interval detected by the pulse interval detector 104 is t _d and the number of light detection areas of the rotary scale 101 is n per rotation, the rotation axis 1
02 is expressed as “2π / (n × t _d ) [rad /
Seconds]].

[0006]

However, in the above-mentioned conventional example, the rotary scale 101 is eccentric with respect to the rotation axis, or the rotary scale 10
If the lens 1 itself is distorted, the center angle of the sensor trajectory between the adjacent photodetectors fluctuates, and a fluctuation synchronized with rotation due to eccentricity and distortion is superimposed on the detected rotational speed. Inconvenience had occurred. In such a case, not only does the accuracy of the detected rotation data decrease, but also the control band is limited by the rotation speed despite the fact that there is a detection band that is n / 2 times the rotation speed theoretically. There was an inconvenience.

On the other hand, it is conceivable to perform eccentricity adjustment by detecting an eccentric component by some method. However, the adjustment itself is very troublesome, and it is practically impossible to correct scale distortion. Has become.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotation speed detecting device capable of accurately detecting the rotation speed of a rotating body without troublesome adjustment even if the rotary scale has eccentricity or distortion. And

[0009]

According to the first aspect of the present invention, there is provided a rotary scale connected to a rotating body via a rotary shaft, and a plurality of rotary scales provided on a scale surface of the rotary scale. A pulse signal forming means for continuously detecting the light reflection portion of the optical signal and converting it into an electric signal; and a pulse interval detector for outputting a predetermined rotation pulse signal based on pulse information outputted from the pulse signal forming means. In the rotation speed detecting device, the rotation shaft is provided with phase pulse output means for outputting rotation information for each rotation of the rotation shaft.

Further, based on the output signals from the phase pulse output means and the pulse signal forming means, a fixed position of each pulse which is displaced due to the eccentricity of the rotary scale is specified, and corresponding to each pulse. An eccentricity coefficient specifying circuit for specifying and outputting a predetermined eccentricity correction coefficient from a table stored in advance is provided. Then, a configuration is provided in which a rotation pulse correction circuit for correcting the pulse interval information from the pulse interval detector described above based on the eccentricity correction coefficient output from the eccentricity coefficient specifying circuit is provided.

For this reason, according to the first aspect of the present invention, when the entire apparatus is set to the operating state, first, the rotary scale is fixed to the rotating shaft and rotates integrally with the rotating shaft.
The reflection-type optical sensor (pulse signal forming means) is placed close to the rotary scale, detects a light reflection portion of the rotary scale, converts the light reflection portion into an electric signal, and generates a rotation pulse signal. Output to the interval detector and the eccentricity coefficient calculation circuit. Further, the phase pulse output means includes:
For example, a phase per one rotation of the rotating shaft is detected and converted into an electric signal to generate a phase pulse signal, which is output to an eccentricity coefficient calculating circuit.

The eccentricity coefficient specifying circuit specifies a fixed position of each pulse which is displaced by the eccentricity of the rotary scale based on output signals from the phase pulse output means and the pulse signal forming means. At the same time, an eccentricity correction coefficient calculated and stored in advance in accordance with the eccentricity of the rotary scale from a table stored in advance corresponding to each pulse is specified for each pulse and output to a rotary pulse correction circuit (multiplier). Further, the pulse interval detector receives the rotation pulse output from the reflection type optical sensor (pulse signal forming means), detects the pulse interval, and outputs the result to a rotation pulse correction circuit (multiplier).

In the rotation pulse correction circuit (multiplier), the pulse interval data output from the pulse interval detector and the eccentricity coefficient data output from the eccentricity coefficient calculation circuit are input, multiplied, and corrected. Is output as the rotation speed data.

According to a second aspect of the present invention, in the rotational speed detecting device according to the first aspect, the phase pulse output means includes: a phase detecting rotary disk having one light detecting area during one rotation; An optical sensor for capturing the light detection region of the rotating disk for phase detection and outputting it as a phase pulse signal is adopted.

Therefore, according to the second aspect of the present invention, in addition to functioning equivalently to the above-described first aspect of the present invention, a phase pulse signal can be reliably output with high accuracy. Therefore, it is easy to identify the position of each pulse in the above-described eccentricity coefficient calculating circuit, and there is an advantage that a section for specifying the eccentricity coefficient of each pulse with high accuracy can be executed with good timing.

According to a third aspect of the present invention, in the rotation speed detecting device according to the first or second aspect, the eccentricity coefficient operation circuit operates using the rotation pulse signal as a count clock and the phase pulse signal as a reset signal. A counter, and a memory in which a counting table of the eccentricity correction coefficient is stored in advance corresponding to each rotation pulse signal, and a memory that sequentially outputs information on the eccentricity correction coefficient in accordance with each rotation pulse signal, The method is adopted.

Therefore, the third aspect of the invention functions in the same way as the second aspect of the invention, and since the eccentricity correction coefficient is calculated and stored in advance, the eccentricity correction corresponding to each rotation pulse signal is performed. There is an advantage that the calculation (specification) and output of the coefficient can be performed at high speed.

According to the fourth aspect of the present invention, the rotary scale connected to the rotating body via the rotary shaft and the plurality of light reflecting portions provided on the scale surface of the rotary scale are continuously detected to generate an electric signal. In a rotation speed detecting device comprising: a pulse signal forming means for converting; and a pulse interval detector for outputting a predetermined rotation pulse signal based on pulse information output from the pulse signal forming means, a reset signal is formed on a rotary scale. A region is provided, and the pulse signal forming means is provided with a phase pulse detector for detecting and outputting a phase pulse signal from pulse information output from the pulse signal forming means.

Further, based on the output signals from the phase pulse detector and the pulse signal forming means, the home position of each pulse displaced by the eccentricity of the rotary scale is specified, and corresponding to each pulse, a predetermined position is determined in advance. An eccentricity coefficient specifying circuit is provided for specifying and outputting a predetermined eccentricity correction coefficient from the stored table. Then, a configuration is provided in which a rotation pulse correction circuit that corrects the pulse interval information output from the pulse interval detector based on the eccentricity correction coefficient output from the eccentricity coefficient specifying circuit is provided.

For this reason, the invention according to claim 4 functions in the same way as the invention described in claim 1 and also has a phase detecting rotary disk required in FIG. 1 to specify the phase of the rotary scale. 5A and optical sensor 5 for phase detection
It is not necessary to use B and the size of the entire device can obviously be reduced accordingly.

[0021]

An embodiment of the present invention will be described below with reference to the drawings. Here, the same reference numerals are used for the same components as those in the above-described conventional example.

[Description of Configuration] First, in FIG. 1, a rotating speed detecting device includes a rotary scale 101 connected to a rotating body via a rotating shaft 102, and a plurality of rotary scales attached to the scale surface of the rotary scale 101. Light reflector 10
An optical sensor 3 as pulse signal forming means for continuously detecting 1a and converting it into an electric signal; a pulse interval detector 4 for outputting a predetermined rotation pulse signal based on pulse information output from the optical sensor 3; It has.

The plurality of light reflecting portions 101a provided on the scale surface of the rotary scale 101 are radially drawn radially in a radial direction and are divided into one as in the case of the above-described conventional example (FIG. 10). It is composed of a plurality (40 in FIG. 10) of strip-shaped light reflection areas set at equal intervals. Further, as the optical sensor 3 described above,
In FIG. 1, a reflection type optical sensor is used.

The rotating shaft 102 has the rotating shaft 1
02 is provided with phase pulse output means 5 for outputting rotation information for each rotation. This phase pulse output means 5
As shown in FIG. 2, a phase detection rotary disk 5A provided with one light detection area 5Aa so as to output one optical pulse during one rotation, and a light detection of the phase detection rotary disk 5A. And a transmission type optical sensor 5B that captures the area 5Aa and outputs it as a phase pulse signal.

The pulse interval detector 4 comprises an oscillator 4A, a counter 4B, and a latch circuit 4C as shown in FIG.
It is composed of Here, the counter 4B counts the number of pulses of the clock pulse signal supplied from the oscillator 4A and outputs a predetermined count value. Also, the counter 4B
Is supplied with a rotation pulse signal from the optical sensor 3 and is reset by the rotation pulse signal. The latch circuit 4C has a function of latching the count value output from the counter 4B by the rotation pulse signal supplied from the optical sensor 3.

Reference numeral 7 denotes an eccentric coefficient calculation circuit. The eccentricity coefficient specifying circuit 7 specifies a fixed position of each pulse which is displaced due to the eccentricity of the rotary scale 101 based on the output signals from the phase pulse output means 5 and the optical sensor (pulse signal forming means) 3 described above. And a function of specifying and outputting a predetermined eccentricity correction coefficient from a table stored in advance corresponding to each pulse.

The eccentricity coefficient calculating circuit 7 is specifically composed of
A counter 7A which operates using the above-described rotation pulse signal as a count clock and the above-mentioned phase pulse signal as a reset signal, and a counting table of eccentricity correction coefficients stored in advance corresponding to each rotation pulse signal, and And a memory 7B for sequentially outputting information on the eccentricity correction coefficient. This memory 7B is constituted by a ROM.

Further, a multiplier 8 is provided as a rotation pulse correction circuit for correcting the pulse interval information from the pulse interval detector 4 based on the eccentricity correction coefficient output from the eccentricity coefficient calculation circuit 7. .

More specifically, the rotary scale 101 is fixed to the rotating shaft 102 and rotates integrally with the rotating shaft 102. Optical sensor (pulse signal forming means)
Reference numeral 3 denotes a light reflecting portion 101a of the rotary scale 101, which is disposed close to the rotary scale 101.
Is detected and converted into an electric signal to generate a rotation pulse signal. This rotation pulse signal is output to the pulse interval detector 4 and the eccentricity coefficient calculation circuit 7.

The rotating disk 5A for phase detection of the phase pulse output means 5 is fixed to the rotating shaft 102 as described above, and rotates integrally with the rotating shaft 102. The transmission type optical sensor 5B is placed close to the phase detecting rotary disk 5A, detects the phase per one rotation of the rotary shaft 102, converts the phase into an electric signal, and converts it into a phase pulse signal. Output to the coefficient calculation circuit 7.

The pulse interval detector 4 receives the rotation pulse output from the reflection type optical sensor (pulse signal forming means) 3 to detect the pulse interval, and multiplies the result by a multiplier (rotation pulse correction circuit) 8. Output to Further, as described above, the eccentricity coefficient calculation circuit 7 holds the eccentricity data measured in advance, and receives the rotation pulse signal output from the optical sensor 3 and the phase pulse signal output from the optical sensor 5B to perform eccentricity. The coefficient data is output to a multiplier (rotation pulse correction circuit) 8.

This multiplier (rotational pulse correction circuit) 8
The pulse interval data output from the pulse interval detector 4 and the eccentricity coefficient data output from the eccentricity coefficient calculating circuit 7 are input, multiplied by these, and output as corrected speed data.

Next, the detailed configuration of the pulse interval detector 4 will be described. As described above, the pulse interval detector 4 includes the oscillator 4A, the counter 4B, and the latch circuit 4C. Here, the counter 4B of the pulse interval detector 4 counts the number of pulses of the clock pulse signal supplied from the oscillator 4A and outputs the coefficient value. The reset terminal of the counter 4B is supplied with a rotation pulse signal from the optical sensor (pulse signal forming means) 3, and the counter 4B is reset by the rotation pulse signal. The latch circuit 4C latches the count value output from the counter 4B by the rotation pulse signal supplied from the optical sensor 3.

Next, the detailed configuration of the eccentric coefficient calculating circuit 7 will be described. As described above, the eccentric coefficient calculating circuit 7 includes, for example, a counter 7A and a memory (ROM) 7 as described above.
It can be realized by a combination of B. The counter 7A counts the number of pulses of the clock pulse signal supplied from the optical sensor (pulse signal forming means) 3, and outputs the counted value. Further, a phase pulse signal is supplied from the optical sensor 5B to the reset terminal of the counter 7A, and the counter 7A is reset by the phase pulse signal. Also, a memory (ROM) 7
B receives the count value output from the counter 7A, and outputs eccentricity data stored in advance as a memory address.

[Description of Operation] Next, the operation of FIG. 1 will be described with reference to the drawings.

First, when the rotating shaft 102 rotates, the rotary scale 101 fixed to the rotating shaft 102 is rotated.
The rotation disk 5A for phase detection rotates. When the rotary scale 101 and phase detection rotary disk 5A is rotated, the rotation pulse signal S ₃ from the reflection type optical sensor (pulse signal forming means) 3 is outputted, also from the optical sensor 5B phase pulse output unit 5 the phase pulse signal S ₅ is output.

The pulse interval detector 4 outputs the rotation pulse signal S output from the optical sensor (pulse signal forming means) 3.
The pulse interval of ₃ is counted by the clock generated by the oscillator 4A, and then latched and output by the latch circuit 4C.

Here, the rotation speed of the rotating shaft 102 is represented by f,
Assuming that the number of the light reflecting portions 101a of the rotary scale 101 is n and the frequency of the clock pulse generated by the oscillator 4A is f _C , the output S ₄ of the pulse interval detector ₄ is between the adjacent light reflecting portions of the rotary scale 1. It represents the transit time. In this case, if the rotary scale 101 is not eccentric or distorted, the sensor trajectory angle θ _dc between the light reflecting portions is constant as shown in FIG. Is constant at t _dc , and the output value of the pulse interval detector 4 is a constant value of “f _C / (f × n)” between all the light reflecting portions.

[0039] If the rotary scale 101 is an eccentric, as shown in FIG. 6 (offset from the center position O ^O, a), the sensor trajectory angle between the light reflecting portion θ _dk (k = 0,1,2, ...
.., N−1) change with the eccentricity. Therefore, even if the rotation speed of the rotating shaft 102 is constant, the transit time between the light reflecting portions does not become constant, and “t _dk = t _dc × (θ _dk / θ _dc ) ”. That is, the output value S ₄ of the pulse interval detector ₄ changes with the eccentricity of the rotary scale 101. This fluctuation rate is uniquely determined by the amount of eccentricity, and is independent of the rotation speed. Here, L indicates a sensor trajectory (relative movement of the sensor position).

Next, the eccentric coefficient calculation circuit 7, the counter 7A will rotational pulse signal S ₃ as counter clock, operates the phase pulse signal S ₅ as a reset signal. Referring to FIG. 7, the output of the counter 7A is "0,
1, 2, takes a value of n-1 ", the value is synchronized with the phase pulse signal S _5. That is, the output of the counter 7A is n light reflecting portions 101a of the rotary scale 101.
Will be assigned an identification number.

Further, in the eccentric coefficient calculation circuit 7, the memory (ROM) 7B, as the eccentric coefficient identification number corresponding to the signal S _7A of the light reflection portions 101a, labeled counter 7A is stored in advance Has become.

In this case, the eccentricity coefficient is obtained as follows. As shown in FIG. 6, when the rotation center is deviated from O ^O, a, between the light reflection portion each other when the rotation speed 2 using the rotary scale 1 there is eccentricity or distortion is rotated at a constant rotational speed f _{c Is} the transit time of t _dc (where k = 0, 1,
..., n-1). Here, k is an identification number (0, 1,..., N) of the light reflecting portion 101a, which is an output value of the counter 7A.
-1).

Assuming that the eccentricity coefficient is β _k , β _k is “β _k =
_tdc / _tdk ". The eccentricity coefficient β _k is stored in advance at an address corresponding to the output value of the counter 7A.

That is, the ratio of the sensor trajectory angles θ of the individual light reflecting portions 101a is stored in the eccentricity coefficient calculating circuit 7. Then, a stored address is generated from the output of the optical sensor 3 as the pulse signal forming means and the output of the optical sensor 5B of the phase pulse output means 5, and the eccentricity coefficient corresponding to each light reflecting portion is output. Will be.

The multiplier 8 serving as a rotation pulse correction circuit includes:
Receiving the transit time data between the light reflectors output from the pulse interval detector 4 and the eccentricity coefficient data output from the eccentricity coefficient calculation circuit 7, the multiplication is performed.

That is, a multiplier (rotation pulse correction circuit)
The output of 8 is “t _dk × β _k = (t _dk / θ _dk ) × θ _dc ”. Here, “t _dk / θ _dk ” means the reciprocal of the rotational angular velocity, which is further multiplied by θ _dc , so that the output t _out of the multiplier 8 is a light reflecting portion obtained from the rotary scale 101 without eccentricity. Between the transit times.

As described above, according to the above-described method, the rotation speed of the rotating body can be detected without being affected by the eccentricity of the rotary scale 101. In other words, even if the rotary scale 101 is eccentric, the same rotation pulse signal S _{3 as the} rotary scale 101 without eccentricity is used.
Can be obtained.

[Other Embodiments] Next, another embodiment of the present invention will be described with reference to FIGS. This FIG.
8 is equipped with a rotary scale 11 having a reset signal forming area in place of the rotary scale 101 provided in the embodiment shown in FIG. 1 and in place of the phase pulse output means 5. And a phase pulse detector 15 for detecting a phase pulse signal from the pulse information output from the optical sensor (pulse signal forming means) 3 described above.
It is characterized by the fact that it is sent to

In this case, the reset signal forming area is as shown in FIG.
As shown in (1), specifically, the rotary scale 11 has a non-reflection area 11b provided in one light reflection section 11a.

Reference numeral 14 denotes a gate circuit provided at the signal input stage of the pulse interval detector 4. The gate circuit 14 is provided to eliminate the malfunction of the pulse interval detector 4 due to the presence of the non-reflection area 11b provided in the light reflection section 11a of the rotary scale 11 for the reset signal. it is obtained so as to capture the signal equivalent to a signal obtained by the reflected light from the reflecting portion 11a from the output of the phase pulse output unit 5 described above as a mask signal S _M. Other configurations are the same as those of the above-described embodiment of FIG.

In this case, the same operation and effect as those of the embodiment shown in FIG. 1 described above can be obtained. In addition, the phase detection rotary disk 5A required in FIG. There is no need to use the optical sensor 5B for detection, and the entire device can be obviously reduced in size accordingly.

[0052]

The present invention is constructed and functions as described above. According to this, even if the rotary scale is eccentric or distorted, the eccentricity coefficient calculating circuit and the rotation pulse correcting circuit are effective as described above. This function corrects the eccentricity and distortion of the rotary scale, which makes it possible to perform accurate speed detection, and in this regard, it is possible to improve the reliability of the entire device. An apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a phase detection rotating disk forming a part of the phase pulse output means disclosed in FIG. 1;

FIG. 3 is a block diagram illustrating an example of a pulse interval detector disclosed in FIG. 1;

FIG. 4 is a block diagram illustrating an example of an eccentricity coefficient calculation circuit disclosed in FIG. 1;

FIG. 5 is an explanatory diagram showing the operation of the eccentric coefficient calculation circuit in FIG. 4;

FIG. 6 is an explanatory view showing an example of an eccentric rotary scale.

FIG. 7 is a configuration diagram showing an example of another embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of the rotary scale disclosed in FIG. 7;

FIG. 9 is a configuration diagram showing a conventional example.

FIG. 10 is an explanatory diagram showing an example of the rotary scale disclosed in FIG. 9;

[Explanation of symbols]

 Reference Signs List 3 reflective optical sensor 4 pulse interval detector 4A oscillator 4B, 7A counter 4C latch circuit 5 phase pulse output means 5A rotating disk for phase detection 5B transmission optical sensor 7 eccentricity coefficient calculating circuit 7B memory (ROM) 8 rotation Multiplier as pulse correction circuit 11, 101 Rotary scale 11a Light reflection unit 11b Non-reflection area 14 Gate circuit 15 Phase pulse detector 102 Rotation axis

Claims (4)

[Claims] 1. A pulse signal forming means for continuously detecting a rotary scale connected to a rotating body via a rotary shaft and a plurality of light reflecting portions provided on a scale surface of the rotary scale and converting the light reflecting portion into an electric signal. And a pulse interval detector that outputs a predetermined rotation pulse signal based on the pulse information output from the pulse signal forming means, wherein the rotation information for each rotation of the rotation shaft is output. A phase pulse output unit is provided on the rotating shaft, and based on the output signals from the phase pulse output unit and the pulse signal forming unit, the home position of each pulse displaced by the eccentricity of the rotary scale is specified. An eccentricity coefficient calculating circuit for identifying and outputting a predetermined eccentricity correction coefficient from a table stored in advance corresponding to each pulse; A rotation pulse correction circuit that corrects pulse interval information from the pulse interval detector based on an eccentricity correction coefficient output from the eccentricity coefficient calculation circuit. 2. The phase pulse output means comprising: a phase detection rotary disk having one light detection area in one rotation; and a phase pulse signal obtained by capturing the light detection area of the phase detection rotary disk. The rotation speed detection device according to claim 1, wherein the rotation speed detection device is configured by an optical sensor that outputs the rotation speed. 3. An eccentricity coefficient calculating circuit comprising: a counter operating with the rotation pulse signal as a count clock and a phase pulse signal as a reset signal; and a eccentricity correction coefficient counting table corresponding to each of the rotation pulse signals in advance. 3. The rotation speed detecting device according to claim 2, further comprising a memory that is stored and sequentially outputs information on the eccentricity correction coefficient in accordance with each of the rotation pulse signals. 4. A pulse signal forming means for continuously detecting a rotary scale connected to a rotating body via a rotary shaft and a plurality of light reflecting portions provided on a scale surface of the rotary scale and converting the light reflecting portion into an electric signal. And a rotation speed detection device including a pulse interval detector that outputs a predetermined rotation pulse signal based on the pulse information output from the pulse signal formation means, wherein a reset signal formation region is provided on the rotary scale, A phase pulse detector for detecting and outputting a phase pulse signal from the pulse information output from the pulse signal forming means; and an output signal from the phase pulse detector and the pulse signal forming means. The home position of each pulse displaced by the eccentricity of the rotary scale is specified based on An eccentricity coefficient calculation circuit for specifying and outputting a predetermined eccentricity correction coefficient from a table stored in advance corresponding to each pulse; and providing the pulse interval detector based on the eccentricity correction coefficient output from the eccentricity coefficient calculation circuit. A rotation pulse correction circuit that corrects pulse interval information output from the motor.